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A convex lens of focal length 40 cm is i...

A convex lens of focal length 40 cm is in contact with a concave lens of focal length 25 cm. The power of the combination is

A

`+1.5`

B

`-1.5`

C

`+6.67`

D

`-6.67`

Text Solution

Verified by Experts

The correct Answer is:
B
Power of convex lens `P_(1)=(100)/(40)=2.5D`
Power of concave lens `P_(2)=-(100)/(25)=-4D`
Now `P=P_(1)+P_(2)=2.5D-4D=-1.5D`
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